i just downloaded windows 8 consumer preview and am not happy with it. I would like to uninstall and go back to windows 7. How do I go about it?

Please note: You can not uninstall the Consumer Preview. To go back to your previous version of Windows, you'll need to reinstall it from the recovery or installation media that came with your PC, and reinstall your programs.

For more info - Windows 8 Consumer Preview FAQ:
http://windows.microsoft.com/en-US/windows-8/faq

Reinstall Windows Preinstalled On Computer
When Windows comes installed with the computer, OEM computer manufacturers are required to provide at least one way for you to reinstall Windows - your computer should have included either a restore partition on your hard drive, or Windows install/restore disks. Most computer manufacturers also have a feature to make your own install disks.

If the restore partition is still there and was not removed, it will reinstall Windows. There is usually a prompt when you first start the computer telling you what key to press to start the restore - check your manual if you're not sure how to. Or if you have install disks - insert them, restart and boot from them to start the reinstall process.

If you restore it to factory condition, it will be like it was when you first bought it - all preinstalled programs will be installed. Anything you installed after buying it must be reinstalled. This will remove any personal files on the computer, back them up first.
 
Preinstalled Windows - if you don't have the recovery partition or install disks:
Contact the OEM computer manufacturer and ask them to send you an install disk for your computer - they may charge a small fee. Contact information for the manufacturer of your computer can be found here:
http://support.microsoft.com/gp/oemphone/